Conventional motorbikes, scooters, bicycles and in-line skateboards, incorporate a steering geometry with a rake and trail. That is, the axis about which the front wheel steers is inclined to the vertical (the rake) and meets the ground at a certain distance (the trail) ahead of the position where the wheel touches the ground. Together, these features strongly influence the stability of the machine. On conventional bikes the angle of the steering axis is inclined to the vertical, leaning upwards, and rearwards from the ground.
However, there are certain advantages in using a rake that is inclined forwards to the vertical. That is, the steering axis leans upwards and forwards from the ground, while still incorporating a trail as described above.
A ‘forward’ leaning rake like this is used extensively on in-line skate boards. A simple caster is typically used, which is inclined forwards to the vertical, creating the rake and trail described above. But these devices do not have trailing arm suspension, and do not have a steering linkage driven from handlebars. Nor do they possess anti-dive brakes as described below.
Likewise, trailing radial arm suspension is very common in all types of motor vehicle. A trailing radial arm is used to allow vertical suspension travel. The radial arm is connected to the wheel axle at one end, and to the remaining chassis at the other, via a horizontal pivot, the wheel axle being positioned behind (trailing) the radial arm pivot.